WARNING in batadv_is_on_batman_iface

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    d8924c0d76aa Merge tag 'devprop-4.21-rc1' of git://git.ker..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=122a373f400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=91a256823ef17263
dashboard link: https://syzkaller.appspot.com/bug?extid=c764de0fcfadca9a8595
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16fd1d67400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+c764de0fcfadca9a8595@xxxxxxxxxxxxxxxxxxxxxxxxx

8021q: adding VLAN 0 to HW filter on device team0
8021q: adding VLAN 0 to HW filter on device team0
8021q: adding VLAN 0 to HW filter on device team0
------------[ cut here ]------------
Cannot find parent device
WARNING: CPU: 1 PID: 9391 at net/batman-adv/hard-interface.c:182  
batadv_is_on_batman_iface+0x3ef/0x460 net/batman-adv/hard-interface.c:182
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 9391 Comm: syz-executor2 Not tainted 4.20.0+ #388
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1d3/0x2c6 lib/dump_stack.c:113
 panic+0x2ad/0x55c kernel/panic.c:188
 __warn.cold.8+0x20/0x45 kernel/panic.c:540
 report_bug+0x254/0x2d0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:271
 do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:290
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:973
RIP: 0010:batadv_is_on_batman_iface+0x3ef/0x460  
net/batman-adv/hard-interface.c:182
Code: 8b 45 d0 48 89 45 c0 e9 f5 fe ff ff 4c 89 ff e8 67 f7 03 fa e9 f4 fc  
ff ff e8 2d ec c0 f9 48 c7 c7 00 16 d6 88 e8 b1 9f 8a f9 <0f> 0b eb b7 e8  
68 f7 03 fa e9 3e fc ff ff 48 8b 7d c0 e8 5a f7 03
RSP: 0018:ffff8881d31e68b8 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff8881d78d0ec0 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8164e075 RDI: 0000000000000006
RBP: ffff8881d31e6900 R08: ffff8881b0d9c040 R09: 0000000000000006
R10: 0000000000000000 R11: ffff8881b0d9c040 R12: 0000000000000000
R13: ffff8881bd630140 R14: 00000000447eea95 R15: ffff8881d78d0fc8
 batadv_is_valid_iface net/batman-adv/hard-interface.c:205 [inline]
 batadv_hardif_add_interface net/batman-adv/hard-interface.c:917 [inline]
 batadv_hard_if_event+0x944/0x11e0 net/batman-adv/hard-interface.c:1041
 notifier_call_chain+0x17e/0x380 kernel/notifier.c:93
 __raw_notifier_call_chain kernel/notifier.c:394 [inline]
 raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401
 call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1733
 call_netdevice_notifiers net/core/dev.c:1751 [inline]
 register_netdevice+0xb98/0x10f0 net/core/dev.c:8570
 ip6gre_newlink_common.isra.29+0x165/0x3c0 net/ipv6/ip6_gre.c:1948
 ip6gre_newlink+0x353/0x9b0 net/ipv6/ip6_gre.c:1981
 rtnl_newlink+0xf08/0x1da0 net/core/rtnetlink.c:3175
 rtnetlink_rcv_msg+0x46a/0xc20 net/core/rtnetlink.c:4950
 netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2477
 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:4968
 netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
 netlink_unicast+0x5a5/0x760 net/netlink/af_netlink.c:1336
 netlink_sendmsg+0xa18/0xfc0 net/netlink/af_netlink.c:1917
 sock_sendmsg_nosec net/socket.c:621 [inline]
 sock_sendmsg+0xd5/0x120 net/socket.c:631
 ___sys_sendmsg+0x7fd/0x930 net/socket.c:2116
 __sys_sendmsg+0x11d/0x280 net/socket.c:2154
 __do_sys_sendmsg net/socket.c:2163 [inline]
 __se_sys_sendmsg net/socket.c:2161 [inline]
 __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2161
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457759
Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7  
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff  
ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fd848638c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457759
RDX: 0000000000000000 RSI: 00000000200005c0 RDI: 0000000000000003
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd8486396d4
R13: 00000000004c49f1 R14: 00000000004d80d0 R15: 00000000ffffffff
Kernel Offset: disabled
Rebooting in 86400 seconds..


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